The Applicant's international PCT patent application number PCT/AU2007/000003 (WO 2007/079524) discloses embodiments of an odour extraction device for a gravity flushing toilet pan. The disclosed odour extraction devices include a fail safe, one way valve to prevent unpleasant odours from flowing from the sewer back to the toilet pan. The disclosed odour extraction devices utilize a suction fan to draw gas from within the pan and expel it through a duct into the pan's flushing outlet pipe. The gas then flows through the pan's flushing outlet pipe into the sewer.
In order to retrofit the odour extraction device to an existing pan, a modification must be made to the pan's flushing outlet pipe to connect the duct thereto. Alternatively, a new pan can be made with a suitable connector for the duct formed therein. Both approaches add to the cost and complexity of the use of the odour extraction device.
Further, the use of odour extraction devices of the type disclosed in the above PCT application with a siphonic toilet have proven unsuccessful. This is due to the connection of the duct to some parts of the pan's flushing outlet pipe compromising the effectiveness of the siphonic flushing action.
It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages